Plasma power controlled synthesis of amorphous to crystalline silicon nanoparticles for high performance lithium-ion battery anodes

Precise control of silicon nanoparticle (Si NP) crystallinity is essential for optimizing lithium-ion battery performance. We report the synthesis of Si NPs with tunable phases, from amorphous to crystalline, using a radio-frequency (RF) low-temperature plasma system. By varying the plasma power from 30 W to 100 W, we achieved a systematic structural transition, as confirmed by XRD and TEM analysis. Post-synthesis carbon coating via CVD was applied to ensure electrical conductivity. Electrochemical tests showed that crystalline Si NPs (100 W) delivered a superior discharge capacity of 1,250 mAh/g and an initial Coulombic efficiency of 87.4%. Notably, crystalline Si exhibited significantly better rate capability than amorphous counterparts, attributed to its structural stability and efficient ion transport. This study demonstrates that plasma power-induced crystallization is a key factor in enhancing the electrochemical performance of silicon-based anodes, providing a practical design strategy for high-performance energy storage.